1. Field
This disclosure generally relates to the field of audio/visual content. More particularly, the disclosure relates to security for a device that stores audio/visual content.
2. General Background
Protected content is often recorded in an encrypted form on a recording device such as a Digital Video Recorder (“DVR”). However, if the content is protected by more than a single content encryption key (“CEK”), it may be difficult to find the correct encryption key during trick plays, e.g., fast forward, jump, skip, etc., and insert the encryption key in time to provide a smooth glitchless user experience. Current approaches do not facilitate such key transitions during trick play modes in a seamless fashion.
In a home setting, it is also reasonable that a second device may wish to access content stored on a home DVR. In many cases, the second device may wish to play back the content before the recording on the DVR is complete. For example, a second device may start playback of a scheduled two hour recording just thirty minutes after it begins. In addition, current approaches do not provide for the second device deriving content keys efficiently in a smooth and glitchless manner while the recording is still in progress.